Carle is arguably the most famous author of children's literature in the U.S. "The Very Hungry Caterpillar" is second only to "Peter Rabbit" in its popularity. With 29 million copies sold, "Caterpillar" is more popular than "Goodnight Moon" and the Dr. Seuss favorite, "The Cat in the Hat." Sales of the book, and its caterpillar-inspired products, bring in an amazing $50 million each year. Carle attributes the popularity of his picture book to its happy message: "It is a book about hope. If you're an insignificant caterpillar, you can grow up to be a big butterfly in the world."

As Newsweek points out, Carle's book about hope is partially inspired by his years spent in Germany during WWII. Carle was born in America to German immigrant parents, but at the age of six, his mother decided to move the family back to Stuttgart. When the war broke out, Carle's father was drafted by the Germans, and Carle remembers spending a good portion of his childhood listening to bombs hit overhead as he hid with his family hid in the cellar. Carle's children's books were inspired, at least in part, by his own difficult childhood:

"With my books," Carle says, "I try to recapture a period I should've had and didn't-for more fun, more nonsense, more humor." But when you know his background it's almost impossible not to look at his work without seeing echoes from his past. Despite the colorful hopefulness of his stories, they're suffused with a sense of loneliness-that solitary caterpillar, making its way in the world. In fact, the opening of "Willi the Worm" read: "This is Willi Worm. He is very hungry. He hasn't eaten through anything for a long time." There's even something about the way he describes the caterpillar's diet ("On Saturday he ate through one piece of chocolate cake, one ice-cream cone, one pickle, one slice of Swiss cheese … ") that evokes the way he describes what he ate after the war when he went to work for the Americans.

Carle now lives in Florida, in a brilliantly colored house by the water with a tidy, well-tended garden. He devotes much of his time to maintaining America's first picture book museum in Amherst, MA, which is currently showing a special exhibition of his work. He also frequently updates his blog, where he writes about his favorite foods (Blackforest honey), run-ins with the local wildlife, and posts pictures of children happily reading his books. "I'm very happy," he says. "In fact, I told my wife I've never been so happy."